title: Clinical assessment of Mycoplasma pneumoniae-associated hemophagocytic lymphohistiocytosis.
abstract: BACKGROUND
  Mycoplasma pneumoniae has been reported to be an etiologic pathogen of infection-associated hemophagocytic lymphohistiocytosis (HLH), but few case reports have been available to date.
  
  
  METHODS
  The clinical features of four childhood cases of M. pneumoniae-associated hemophagocytic lymphohistiocytosis (Mp-HLH) were retrospectively assessed to obtain data that might be useful for early diagnosis and effective management. The previous English-language literature pertaining to Mp-HLH was also reviewed.
  
  
  RESULTS
  The patients were two boys and two girls, aged between 1 and 11 years of age. One patient was demonstrated to have concurrent infection with rubella. All the patients had typical radiographic features of M. pneumoniae pneumonia, and one patient also had encephalopathy as a complication. All the children underwent bone marrow examination because of antibiotic-refractory fever, mild hepatosplenomegaly, cytopenia, hyperferritinemia and elevated levels of urine beta2-microglobulin. Cytopenia and hepatosplenomegaly in the present patients were relatively mild as compared to those in cases of other infection-associated HLH such as Epstein-Barr virus infection-associated HLH. Treatment with corticosteroids resulted in prompt and complete resolution in two cases, and i.v. high-dose gammaglobulin therapy achieved a complete response in another child. Spontaneous resolution under treatment with antibiotics alone was observed in one case.
  
  
  CONCLUSIONS
  Although Mp-HLH is a rare complication of M. pneumoniae infection, it should always be considered in patients with antibiotic-refractory M. pneumoniae infections with cytopenia. Mp-HLH might be effectively treated by corticosteroids or high-dose gammaglobulin. To clarify the diverse clinical manifestations of M. pneumoniae infections, immunological interactions between M. pneumoniae and the host immune system should be further investigated.
authors.affiliation: Department of Pediatrics, Wakayama Medical University, School of Medicine, Wakayama City, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Yoshiyama
authors.forename: Shinji
authors.initials: S
authors.lastname: Kounami
authors.forename: Keiko
authors.initials: K
authors.lastname: Nakayama
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Aoyagi
authors.forename: Norishige
authors.initials: N
authors.lastname: Yoshikawa
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D051359:Lymphohistiocytosis, Hemophagocytic / Q000175:diagnosis / Q000209:etiology*; D008297:Male; D011019:Pneumonia, Mycoplasma / Q000150:complications* / Q000175:diagnosis; D012189:Retrospective Studies